Method of chemically disintegrating and pulverizing solid material



United States Patent METHOD OF CHEMICALLY DISINTEGRATING AND PULVERIZIN G SOLID MATERIAL Rintaro Takahashi and Takehiko Yuize, Tokyo, Japan No Drawing. Application August 23, 1955 SerialNo. 530,205

Claims priority, application Japan May 4, 1955 14 Claims. (Cl. 75-.5)

This invention relates to amethod of chemically disintegrating or pulverizing solid material and more particularly to a method of chemically destroying or pulverizing compact and hard solid material or sintered carbide alloys.

It is an object of the present invention to provide means for chemically disintegrating or coarsely crushing compact and hard solid material such as ores, sintered pieces, pottery or porcelain fragments and concrete fragments with ease.

Another object of the present invention is to provide a method of chemically, readily and rapidly disintegrating or pulverizing solid material, especially hard alloys whose main components are carbides such as WC, TiC,

'TaC, BC, MoC, ZrC and the like and which contain Ni carbide powder which has an alloy layer made between one or more metal carbides and other metals on the surface or on a part thereof of the metal carbides.

Other objects, features and advantages of the invention will be apparent from the following descriptions.

Heretofore, to disintegrate compact and hard material such as oresor sintered compacts, mechanical methods have mainly been adapted. for ores, and also, only mechanical processes have been practically employed for. sintered materials (mainly sintered carbide alloys), while acid dissolving methods and electrolytic methods are only used in studying fields, since these methods are not commercially practicable. For ores also the advent of some excellent disintegration method is desired. Such mechanical methods, have many deficiencies, such as large loss of energy, the requirement of many man hours, marked wear and damage of machines and tools employed, and so on.

On the other hand, the quantities of hard alloys to be used have recently increased remarkably and thus the volume of waste materials, rejected products and fragments of these alloys amount to a considerable quantity.

--As W, Ti, Ta, Mo, Zr, Ni, Co and the like contained in those materials are each very valuable, it is an important industrial problem to destroy or crush the original form of those alloys and further, when desired, to separate each valuable element contained therein, to recover and reclaim it.

Hitherto, the disintegration of this kind of hard alloys has generally been impossible and nosimple method for disintegrating such alloys has been yet proposed. As the only methods for recovering the elements contained in such alloys, the following methods have been suggested;

of disintegration (perfect disintegration being impossible);

a method for recovering W0 and Co dissolved by anodic oxidation in electrolysis and a method in which Co is r6 CC dissolved by boiling in non-oxidizing strong inorganic acid of a certain concentration to leave WC in porous form which is then mechanically destroyed and recovered. In these methods, W0 is reduced and then carbonized, and Co is recovered from the solution in the form of a compound or an element, or the materials must be disintegrated mechanically. All of the hard alloys which have been reclaimed secondarily by employing those recovered by any of these methods as raw materials are remarkably inferior to primary ones in toughness and cutting ability, and thus many products are rejected, so that the industrial reclamation of hard alloys by these methods has been difiieult to practice up to the present. The reason is believed to be that the properties of W powder and WC powder are unfavorably influenced by imperfect oxidation, reduction, and carbonization and also the tendency of impurities to contaminate them is remarkable.

This invention is to solve industrially the method of chemically and simply disintegrating or pulverizing compact and hard solid materials or certain hard alloys, as described above, and further to recover valuable elements contained in such hard alloys, when desired. Furthermore, the invention is contemplated to utilize the advantages of the powder obtained by such disintegrating method.

The present invenion is characterised in that, in disintegrating or pulverizing solid materials such as ores and other compact and hard solid materials or hard alloys whose main components are carbides, such as WC, TiC, BC, MoC, ZrC and the like and which contain Ni, Co or Ni-Co as their cementing material, these solid materials are subjected to the action of a fluid such as a gas or a liquid substance for example, chlorine gas, halogen gas, fusedFeCl solution and fused CaCl solution so that a part of the constituent element thereof is changed to a compound which greatly expands its volume by containing the water of crystallization or a substance which greatly expands its volume -by containing the water of crystallization is caused to permeate into the solid material and then to take up the water of crystallization to produce heavy stresses in the solid material in order to destroy or pulverize the solid material in cooperation with the action of internal stress, or a gas such as CO is made to act on the cementing material in the solid mate-- rial to change it into a carbonyl compound so that at the same time the original form of the solid materials is: disintegrated.

According to the invention, compact and hard solid materials can be easily coarsely disintegrated or pulverized. The method'according to the invention'can be very efiectivelyapplied to the disintegration of materials such as ores, sintered compacts, potteries and porcelains, concretes, and the like. Hence the method according to the invention is very valuable in mining and manufacturin'g industries.

According to the present invention, in disintegrating compact and hard solid material, gas such as chlorine gas or a liquid substance such as fused CaCl solution is caused to permeate into the surface of the solid material. In the case of gas the gas is caused to act on oneof the constituents of the solid material to produce a cornpound which greatly expands its volume by containing the water of crystallization, while in case of a liquid substance a compound which greatly expands its volume by containing the water of crystallization is caused to permeate in the solid material and then the volume of the compound is expanded by imparting the water of crystallization thereto in air, in water, or in an aqueous solution so as to produce heavy stresses in the solid material. Thus, the solid material is coarsely destroyed by the utilization of the action of the inner stress, for example 3 quenching stress, when quenched. As most of the compounds containing the water of crystallization which is produced after the destruction are deliquescent and easily soluble in water, they can easily be separated or removed from the solid. Thus, this method is very effective when applied to the disintegration of compact and hard materials which can hardly be destroyed by the mechanical or electrolytic methods.

Next, in disintegrating or pulverizing hard alloys whose main constituents are carbides such as WC, TiC, BC, MoC, ZrC and the like and which contain Ni or C or Ni-Co as their cementing material, the original form of the alloys is disintegrated by changing the cementing material for carbides described above, such as Ni and Co, or Ni, or C0, to its carbonyl compound by the action of carbon monoxide gas on the cementing material at an ordinary temperature or under heat and pressure in a suitable vessel. Further, when desired, the carbonyl compound of Ni or C0 or Ni-Co is decomposed at a room temperature or under heating and pressure and the powder elements of Ni and Co may be produced on one hand and the carbon monoxide gas produced by the decomposition may be recovered on the other hand and used repeatedly.

According to the features of this invention as described above, the disintegration of solid materials is due to the reaction between gas and the solid material so that the disintegration proceeds quite rapidly, and in the case of coarse crushing this object can be also attained by the reaction on the surface of the material. Also, pure gas is easily obtained with substantially no possibility of contamination by impurities.

Thus, according to the present invention, there are obtained desirable advantages in that the carbon monoxide recovered can be repeatedly used and that the desired destroying operation can be effected through in a single vessel as described above. These advantages can never be expected in the hitherto known methods. In addition, according to this invention, Coand Ni powders can be recovered in minute particle size by controlling the time, pressure and temperature of the decomposition. For instance, the size of Co powder used for the primary product is about 20 microns while that of the powder recovered in accordance with the invention is of the order of 2 to 3 microns. Therefore, when such fine powder of Co is used, the time required for mixing with WC is quite short. For instance, the time required for mixing in the case of the primary products is more than fifty hours, whereas only 4 to 5 hours is enough when the fine powder described above is used. Further, according to the invention a large quantity of WC of the size of 1 to 2 microns and less than 0.2 micron can be recovered in very irregular shapes. However, WC as raw material for the primary products is in the size of the order of 3 to 5 microns, its shape being generally square or multangular.

The C0 and WC thus recovered are reclaimed by directly pressing the material into dies and then by sintering without the need for special mixing. The secondary products thus obtained are superior remarkably to the primary products in their toughness, cutting ability, wear proofness and the like.

The above-mentioned method of alloy disintegration according to the invention is especially advantageous when the hard alloy which is solid material is rather small in volume. There often are, however, many considerably voluminous objects such as armor-piercing caps, large dies and the like, in wastes of hard alloys. When these voluminous solid materials are directly treated by the carbonylization process according to the invention, much time is required. However, in destroying the materials as described above by the carbonylization method according to the invention, the crushing operation can be made markedly effective by the pretreatment according to the aforesaid disintegration method, in which the water of crystallization is utilized. Thus, the method according to the invention can also be advantageously applied to the disintegration or pulverization of solid materials which are comparatively large in volume.

The invention is further described in the following examples, which are illustrative but not limitative thereof.

Example 1 Compact and hard unglazed pottery or concrete was immersed in fused CaCl to cause CaCl to permeate into its surface and then was taken out and left in air or put into water. Thus, CaCl was changed into CaCl 6H O and the solid material containing the latter was gradually disintegrated allowing CaCl 6H O to deliquescence or dissolve in water so that, by removing the latter a granular solid can be obtained. Since the change ofspecific gravity of CaCl to CaCl 6H O is smaller than that in the following examples, the method was less effective for solid materials containing coarse pores.

Example 2 Waste tips of class G, namely WCCo system hard alloy materials, were heated at 800 to 850 C. for 30 to 60 minutes in a tube furnace while feeding chlorine thereinto, after which the feeding of C1 gas was stopped. When the pressure in the furnace was reduced to vacuum and the temperature was raised to l,000 C., the cementing material, Co or Ni was changed to CoCl or NiCl by C1 gas to the depth up to several millimeters from the surface of the alloy and these compounds vaporized by vacuum heating cracked the surface layer of the waste tips. The solidmaterial was thus disintegrated by repeating this operation several times.

Example 3 Waste tips of class G namely, WC-Co system hard alloy materials were heated in a chlorine gas stream at 800 to 850 C. for about thirty minutes or an hour (this time is shortened under pressure) and were quenched in water, and allowed to cool. They were roughly disintegrated in a short time, became fine granules within five or six hours, and were then well washed in hot water to remove the soluble Co. When a small quantity of tungsten oxide still remained, it was removed by hot alkaline solution and W in this solution was recovered in the form of W0 The remaining solids that is, the granules, in which undissolved Co was still present around the surface of WC were changed into a fine powder containing mostly grains of less than 0.2 micron by lightly rubbing said granules in a mortar, accompanied by water washing and drying. When the solid was treated by the method as described above, very fine powder of WC containing a little amount of Co could be obtained. In the disintegration according to this invention, C1 gas reacted on Co as a cementing material of hard alloys to produce CoCl (blue in colour), which, after being put in water, produced the water of crystallization of CoCl 6H O (red). Thus, Co was changed into crystals expanding its volume as much as more than four times. This is the same phenomenon as seen when wedges are driven into the surface of the solid. Accordingly, a large stress was produced in the solid and brought about the phenomenon of disintegration in cooperation with the quenching stress and the stress previously produced by working. Further, CoCl 6H O is fortunately very water soluble so that CoCl changed to CoCl 6H O and at the same time, dissolved in the water with which it makes contact. This is why the action combining the water of crystallization and CoCl into CoCl 6H O, proceeds rapidly into the interior of the solid, thus promoting the phenomenon of disintegration as time goes by. However, the production of tungsten chloride due to the decomposition of WC in hard alloys could not be observed at the temperature described above. Since a part of CoCl on the solid surface evaporates, the vapor can be cooled and collected in an aqueous solution so as to be recovered together with C dissolved in water at the time of quenching described above. 'Hard alloys other than class G, in which a part orthewhole of Co issubstituted by Fe, Ni, Cr or Mn,

can be converted into fine grains by the similar treatment.

Example 4 Thehard alloy covered with sulphur powder was heated at about 500 C. for thirty minutes in dry air to change C0 inthe alloy to C080 which was put in water as in Example 5 An example of treating waste products of the WC-Co system hard alloys (Co 6%, WC 94% About 120 gr. of the waste of the size of 2 to 3 mm. was put in a glass-lined autoclave, into which pure carbon monoxide gas was introduced to react on the waste. By heating to approximately 200 C. under pressure of over 100 atm. while rotating, crystalline powder of Co (CO) (orange-red in colour) was produced on the surface of the hard alloy. As the rotation of the autoclave was continued for the further reaction, the crystalline powders of Co (CO) separted and the reaction proceeded to the inner part so that WC (dark grey in colour) crumbled and thus the original form of the alloy was entirely reduced to powders in about four hours, in which case only carbides such as TiC, BC, ZrC, etc. were not affected by the chemical action of carbon monoxide gas and remained intact.

In this case, for the individual separation of Co and WC, the mixture of WC and Co (CO) may be treated with an organic solvent such as ethyl alcohol or ether at room temperature and under normal pressure, to dissolve Co (CO) the insoluble WC being filtered Ofi by filtration. By heating the solution to above 60 C., metallic powders of Co can be obtained.

Furthermore, as the autoclave continued to rotate while keeping the powders obtained by the disintegration of the alloy at a temperature higher than about 60 C. under normal pressure, Co (CO) was decomposed into Co and carbon monoxide gas, the latter being gradually removed and recovered for repeated use. Moreover, the decomposition of Co (CO) proceed comparatively rapidly, thus CO (CO) being changed into Co element and carbon monoxide in a short time. As the autoclave turns, two operations are effected, that is, the reaction is promoted and at the same time the mixing of WC and CO is efllected. When Co (CO) had been perfectly decomposed into Co element, 118 gr. of CoWC mixture was obtained. In-the powder mixture of the metal and carbide, WC and Co are in such a state that particles of Co cover the surface of WC particles. The powder mixture was compressed in dies under pressure of 5 to 30 t./in. by hot or cold pressing, a small quantity of a lubricant, such as stearic acid or paraifin, being used in case of cold pressing. The formed material was sintered for 15 to 50 minutes at temperatures of 900 to 1,000 C. in hydrogen gas stream in a carbon tube furnace, depending upon the Co content. After the primary sintering operation, the material was covered with graphite powder and further sintered for one or two hours at 1,350 to 1,500 C., in the same manner as in the primary sintering. Thereafter, the sintering was ended.

Example 6 An example for the WC--TiC-Co system hard alloy will now be described.

In this alloy, WC-TiC exists in the state of solid solution so that it can be disintegrated by the same treatment as for the WC-Co system hard alloy described above. In addition, Co and WC can also be recovered in the same manner.

Thus, according to the invention, the wastes or scraps of hard alloys may be treated and reclaimed as raw materials of hard alloys in the manner as described above. The operation is simple and can be completed in a very short time as compared with that for treating new primary raw materials.

What we claim is:

l. The process of disintegrating scrap material which comprises treating said scrap with a dehydrated fluid which is taken up by said scrap, and thereafter hydrating said fluid-treated scrap, whereby internal stresses are created within said scrap with disintegration thereof.

2. The process of disintegrating scrap material which comprises treating said scrap with a fused metal chloride which is taken up by said scrap, and thereafter hydrating said scrap, whereby said chloride undergoes expansion with creation of internal stresses serving to disintegrate said scrap.

3. The process of disintegrating scrap comprising hard metal carbide and a metallic bond, which comprises treating said scrap with a fluid which is reactive with said metallic bond to produce a deliquescent product, and hydrating said deliquescent product whereby the resulting expansion causes said scrap to disintegrate, the hard metal carbide being left as a powder.

I 4. The process of claim 3, including the further step of dissolving out the hydrated product to separate the hard metal carbide powder.

5. The process of disintegrating scrap comprising hard metal carbide and a metallic bond, which comprises heating said scrap with sulfur in oxygen to thereby form the sulfate of said metallic bond, and dissolving out said sulfate to thereby disintegrate said scrap and deposit said hard metal carbide as a powder.

6. The process of claim 5, wherein after conversion of the bond to the sulfate said scrap is permitted to hydrate, the sulfate being converted to the hydrate with expansion which serves to disintegrate said scrap.

7. The process of disintegrating scrap comprising hard metal carbide and a metallic bond, which comprises heating said scrap with gaseous chlorine whereby the bond material is converted to the chloride, and dissolving out said chloride to thereby disintegrate said scrap and deposit said hard metal carbide as a powder.

8. The process of claim 5, wherein after conversion of the bond to the chloride said scrap is permitted to hydrate, the chloride being converted to the hydrate with expansion which serves to disintegrate said scrap.

9. The process of disintegrating scrap comprising hard metal carbide and a metallic bond, which comprises treating said scrap with a gas containing carbon monoxide whereby the metallic bond forms a carbonyl powder, said scrap thereby being disintegrated and depositing the hard metal carbide as a powder.

10. The process of claim 9, wherein the mass is treated to decompose said carbonyl into free metal powder which at least partly coats the surface of said hard metal carbide powder.

11. The process of claim 9, wherein said metallic bond comprises cobalt.

12. The process of claim 9, wherein said metallic bond comprises nickel.

13. The process of disintegrating material containing a substance convertible into a sulfate which comprises treating said material to produce a sulfate therein, and contacting said treated material with water whereby said sulfate is hydrated with a resultant increase in volume thereby producing internal stresses and causing said material to disintegrate.

14. The process of disintegrating material which comprises chemicaly reacting said material with sulfur to 7 convert at least one element thereof into a sulfate therein and contacting said reacted material with water whereby said sulfate is hydrated with a resultant increase in volume thereby producing internal stresses and causing said material to disintegrate. 5

References Cited in the file of this patent UNITED STATES PATENTS 505,408 Moore Sept. 19, 1893 10 

9. THE PROCESS FOF DISINTEGRATING SCRAP COMPRISING HARD METAL CARBIDE AND A METALLIC BOND, WHICH COMPRISES TREATING SAID SCRAP WITH A GAS CONTAINING CARBON MONOXIDE WHEREBY THE METALLIC BOND FORMS A CARBONYL POWDER, SAID SCRAP THEREBY BEING DISINTEGRATED AND DESPOSITING THE HARD METAL CARBIDE AS A POWDER.
 10. THE PROCESS OF CLAIM 9, WHEREIN THE MASS IS TREATED TO DECOMPOSE SAID CARBONYL INTO FREE METAL POWDER WHICH AT LEAST PARTLY COATS THE SURFACE OF SAID HARD METAL CARBIDE POWDER. 